1. Field of the Invention
The present invention relates generally to water-repellent compositions adapted for use with masonry products and more particularly to such a water-repellent composition that is storage stable. The composition of the invention combines a relatively water-insoluble hydrolyzable silane and a hydrogen-functional polysiloxane in the form of an aqueous emulsion.
2. Description of the Prior Art
The beneficial effects of the using water-repellent compositions to protect masonry materials are well-known. As used herein, the term "masonry" means any porous inorganic substrate, particularly building compositions and including but not limited to structural ceramics, such as common brick, paving brick, face brick, sewer pipe, drain tile, hollow block, terra cotta, conduits, roofing tile, cements and plastics such as Portland cement, calcined gypsum products, i.e., molding and building plasters and stucco, magnesia cement, insulation products such as electrical insulators and natural and artificial stone. Because of their porosity, in the untreated condition these materials can readily absorb ambient moisture. Subsequent exposure to freezing temperatures can cause fracture, resulting in cracking and spalling. In the case of masonry materials used for constructing roads and bridges, the water repellent coatings also serve to protect the masonry materials from the deleterious effects of salt.
In U.S. Pat. No. Re. 33,759, DePasquale et al., there is disclosed a composition, in the form of an aqueous emulsion, for rendering masonry materials water-repellent. The claimed composition consists essentially of a hydrolyzable silane, or an oligomer thereof, an emulsifier having an HLB of from 4-15, and water. When prepared by the present inventors, the compositions of DePasquale et al. suffer from the drawback that they offer only limited shelf stability, which is exacerbated by exposure to heat.
In U.S. Pat. No. 5,110,684, Cooper, there is disclosed a water-repellent composition for masonry which includes a mixture of a water-soluble silane coupling agent and an emulsion of a hydrogen-functional polysiloxane. The composition of Cooper, however, also suffers from the drawback that it is has a very limited shelf life.
Thus, there exists a need for a water-repellent composition adapted for use with masonry products that is storage stable.